I don't have a picture handy, but on my 304 with the TY395i-3 engine he governor part of the injector pump is on the right hand side as you are looking at it, the part where the throttle linkage attaches.
On some of the Chinese injector pump assemblies, there are two drains for the thing - one on the bottom of the governor and one on the bottom of the pump itself. The total oil volume is about twenty ounces. A number of guys have missed that second drain plug and drained only half the assembly so it only took ten or so ounces to fill it. (My pump assembly only seems to have one drain plug for some reason.) If you happen to have missed the other drain on yours, you might still have old oil in the governor part. There is only one fill point, by the way, the breather cap thingy on top of the pump. The oil spills over from one side to the other when filling, but has to be drained separately to get it all out.
If it is something amiss inside the governor like Bob suggested it might be, I think the conventional wisdom is that you really need an expert to do any messing around inside the governor due to the precise clearances and need for exact settings.
Don't know if this helps or not, but there it is. Once again, best of luck with it.
Rich